The suspect in a shooting at a leading French newspaper office had lived in Britain for several years before returning to France in July, according to the Associated Press.
Abdelhakim Dekhar remains in custody in a suburban Paris hospital after police detained him on Wednesday night, the Paris prosecutor said.
Prosecutor Francois Molins told reporters that the witness who turned Dekhar in said he had been staying with him and that they had met while working in a restaurant together in London 13 years ago.
More top news
More than 120 famed actors and music stars said they are using their "privilege to speak out" to warn of Trump's "real and present threats".
A character is seen carrying a tray of hot drinks before slipping on some paper, with one sheet appearing to be covered with Arabic script.
A historic night in Philadelphia saw mixed emotions as a bitter rivalry was settled before Bill Clinton made his pitch for his wife to lead.